1. Field of the Invention
The invention is generally related to reversible, mechanically interlocking polymer networks which self-assemble in a reversible manner.
2. Description of the Prior Art
Both branched polymers and physically interlocked polymer systems have become very active research fields because of the potential for property tailoring and customization made possible due to the molecular architectures of these molecular systems.
As schematically depicted in FIG. 1, branched polymer materials 1 can be prepared by one-step reactions of AB.sub.x monomers, in which functional groups A and B react with each other and the coefficient x has a value of 2 or greater.
On the other hand, interlocking molecular systems of recent interest include rotaxane complexes. As schematically depicted in FIG. 2, rotaxane complexes are formed by noncovalent interactions between a main chain linear molecule 2' and a cyclic molecule (i.e., a macrocycle) 2" which results in physical "threading" of the cyclic molecule 2" onto the linear molecule string 2'. E.g., see Gibson, H., Large Ring Molecules, Semlyen, J. A. ed., J. Wiley and Sons, New York, 1996, 191-262. Strong driving forces are necessary for the threading to occur extensively. For example, sufficient inclusion complexation in this regard has been reported for cyclodextrin-based polyrotaxanes and sufficient hydrogen bonding in this regard has been reported for crown ether-based polyrotaxanes. E.g., see Harada, A., et al., Macromolecules 1995, 28, 8406; Gibson, H., et al., J. Am. Chem. Soc. 1995, 117, 852-874. Also, sterically large terminal blocking groups BG are often desirably formed on the linear molecular 2' string to prevent the decomplexation of the cyclic molecule 2". Many rotaxane complexes function as molecular "shuttles" by moving back and forth between identical stations along the length of the linear polymer.
U.S. Pat. No. 5,538,655 describes molecular complexes having rotaxane structures for use as electrolyte components. The electrolyte uses the molecular complex for ion transport via back and forth shuttling motions of the linear molecules of the rotaxane structures to effect ion transport through the electrolyte while polymerized cyclic molecule components of the rotaxane structures anchor the network complex. This ion transport function requires an ultimate polymerized molecular complex that is irreversibly formed. That is, the electrolyte using the molecular complex with rotaxane complexes for ion transport in this manner can include solvents which solubilize or gel (swell) the molecular complex but which implicitly do not dissociate the polymer back into the individual corresponding constituent polymers, as such dissociation would preclude the stated ion transport function of the molecular complex.
Against this background, it is an object of the present invention to construct complex, mechanically linked, reversible networks of polymers and copolymers for self assembly at a molecular level.